Bioconcentration, metabolism and the effects of tetracycline on multiple biomarkers in Chironomus riparius larvae

The antibiotic tetracycline (TC) is widespread in surface waters, but few data are available regarding its adverse effects on aquatic insects. In this study, we investigated the bioconcentration, metabolism, and effects of TC on Chironomus riparius larvae exposed to different concentrations of TC (1.83, 18.5 and 174 mu g L-1) for 48 h. The bioconcentration factors were 3.65,0.74 and 0.23 in larvae with exposure to 1.83, 18.5 and 174 mu g L-1 TC, respectively. High concentration ratios of the metabolites anhydrotetracycline (0.56-0.60), 4-epitetracycline (0.43-0.69), and 4-epianhydrotetracycline (0.50-0.55) to the unmetabolized compound were found. Additionally, the activities of superoxide dismulase and glutathione S-transferase were markedly inhibited with a significant increase in malondialdehyde contents at high exposure concentrations of TC (18.5 and 174 mu g L-1). Moreover, significant up-regulation of heat shock genes (hsp70 and hsp27), the ecdysone receptor gene, and the E74 early ecdysone responsive gene was observed at all exposure concentrations except for hsp70 at 1.83 mu g L-1. Collectively, these results suggested that TC was quickly absorbed and metabolized by C. riparius and resulted in molecular and biochemical disturbances. (C) 2018 Published by Elsevier B.V.